Sheet metal roof panels are well-known in the art. They are typically attached in a manner similar to that utilized for wooden, slate, or asphalt shingles. That is, the individual panels are placed in an overlapping configuration, the overlapping region is then nailed down to the roof substrate.
This system, while suitable for wooden, slate or asphalt shingles, results in a number of difficulties when applied to sheet metal roof panels. For one, sheet metal roof panels are usually larger than shingles. As a result, high winds tend to generate a strong uplift on the panels. Given this tendency, an especially strong physical connection is required between the sheet metal panels and the roof substrate.
When high winds do in fact uplift sheet metal panels, there is a displacement of the nails used to connect the panels to the roof. The displacement of these elements destroys the seal between the elements. As a result, moisture passes through the holes left by the nails. This moisture tends to cause rotting of the roof substrate while also inducing the panels to rust.
A related problem stems from the fact that the rigid connection between the roof, the sheet metal panels and the nails expands and contracts under the extreme temperature variations experienced on a roof. This is primarily a consequence of the relatively high thermal coefficient of expansion of metal compared to wood. Since the connection between these elements is not yielding in nature, the connection often fractures and is otherwise subject to displacement. Again, moisture migrates beneath the sheet metal panels and therefore weakens the roof structure while promoting the rusting of the roof panels.
The prior art has attempted to avoid some of these problems by using liquid cement to bind sheet metal panels to the roofing substrate. However, this approach is problematic insofar as it involves the labor-intensive activity of applying the liquid cement. In addition, since the drying time of the bonding materials varies greatly with weather conditions, a great deal of time is spent waiting for the bonding material to approach an appropriate state. Occasionally, bonding is attempted at inappropriate times, resulting in inferior bonding characteristics. Moreover, liquid cements are generally rigid and non-elastic.
In the prior art, roofing paper is commonly utilized in order to facilitate roof replacement and removal. That is, the roofing paper shears upon removal of the roof and leaves a clean surface which can be immediately used for installation of a new roof. Application of roofing paper is a discrete step in the process of building a roof. As such, it is time consuming and expensive.